Sophos service searches for zombie PCs

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Anti-virus firm Sophos has launched a service that notifies organisations if any of their PCs are taken over by hackers. The ZombieAlert Service is designed to automatically notifies subscribers about exploited and hijacked computers on business networks.

Trojans such as Phatbot are often used to seize control of Windows PCs, turning them into zombie clients in networks of compromised PCs (botnets). These botnets are used to send spam or as platforms for DDoS attacks, carrying out criminal attacks right under the noses of their rightful owners. The tactic allows hackers to offload the computing effort in sending spam while creating a means to get past basic junk mail filters.

SophosLabs reckons more than 50 per cent of all spam originates from zombie computers. As spammers become more aggressive, collaborating with VXers to create botnet armies of zombie computers, legitimate organisations with hijacked computers are being identified as a source of spam. This not only harms the organization’s reputation, but can also cause the firm’s email to be blocked by others.

ZombieAlert fires off a warning if spam from a subscriber's domain is trapped in Sophos's network of spam traps. It also provides notification to customers if their Internet Protocol (IP) addresses are listed in public Domain Name Server Blackhole Lists (DNSBL). These alerts help customers to locate problems and clean up their systems before spam sent from their domain becomes the subject of widespread complaint. ZombieAlert is part of Sophos's premium and platinum support packages. It can also be purchased as a standalone subscription at, for example, $2,500 for organisations with up to 1,000 seats.

Cleansing the net from the plague of zombie spam networks has become the focus of a number of industry initiatives over recent months. ISPs are encouraged to apply rate-limiting controls for email relays and to block port 25 (a common Internet port used for email) from inappropriate use as part of an educational campaign called Operation Spam Zombies, launched by the US Federal Trade Commission (FTC) and government agencies worldwide in May 2005. ISPs are also being urged to educate consumers about net security and to provide tools to disinfect computers under one of the most ambitious net security education initiatives to date. ®